Cartridge-actuated fastener driving tool



Filed Feb. 28. 1967 United States Patent O M' 3,489,329 CAR'mIDGE-ACTUATED FASTENER DRIVING TOOL Hans-Dieter Seghezzi, Furstentum, Liechtenstein, assignor to Hilti Aktiengesellschaft, Schaan, Liechtenstein Filed Feb. 28, 1967, Ser. No. 619,349 Claims priority, application Great Britain, Mar. 5, 1966, 9,728/ 66 Int. Cl. BZSc 1/12 U.S. Cl. 227-9 2 Claims ABSTRACT OF THE DISCLOSURE Apparatus for securing identification plates, or the like, to articles, such as hot metal billets, includes to cartridgeactuated fastener driving tool mounted on a support for movement between operative and inoperative positions. In the operative position, the tool, and a locator means for locating an identification plate relative to the tool for securing to an article by the tool, confront an article. In the inoperative position, the tool is displaced from the operative position. The tool has a cartridge chamber for receiving a cartridge, and remote actuating means are perable to actuate the tool when the latter is in its operative position, as by firing the cartridge.

A plastic case cartridge is used in the fastener driving tool, and can be fired by application of an electric potential thereto, the potential having to be above a predetermined value. For this purpose, the plastic case cartridge has a pair of contacts thereon which, when the cartridge is placed in the cartridge chamber in the tool, are engaged with a pair of mating contacts connected to a selectively closable electric ignition circuit. The electric ignition circuit includes a voltage step-up transformer and a plurality of `switches in series, serving as safety switches, and all of which must be closed in order to permit a potential to be applied to the cartridge. Additionally, novel means are provided for closing the cartridge chamber and resisting the explosive force when the cartridge is detonated.

CROSS REFERENCE TO RELATED APPLICATION The present invention is an improvement on the article marking apparatus shown, described and claimed` in the copending application of Wolfgang Bayer, Ser. No. 554,- 804, filed June 2, 1966, now Patent No. 3,368,730, issued Feb. 13, 1968 and assigned to the assignee of the present application. The apparatus of the present application is, in large part, the same as the apparatus of this copending application, the improvement over the copending application residing in a new construction of the fastener driving tool for use with plastic case cartridges and in the provision of electric igniting means for the plastic case cartridge.

BACKGROUND OF THE INVENTION In the steel and like industries, considerable difiiculty has been experienced in applying identification markings to metal slabs, blooms, billets and the like. The marking of slabs, blooms, billets, and the like after rolling and for subsequent identification has been effected in a number of ways, none of which has been completely satisfactory. Thus, chalking or marking with some other medium can =be effected only after rolled article has cooled to near room temperature, and thus can be done only a considerable time after rolling and usually after the rolled article has been stockpiled. Such marking thus becomes a separate operation unrelated to the actual rolling of a billet or ingot to form a slab or bloom. Consequently, as the marking has no direct correlation with the rolling operation, the identification is subject to error, in addition to ICC which the markings tend to become erased or obliterated while the articles are stockpiled.

Another proposal has been to weld identification plates to slabs or blooms after rolling and while they are still hot. This, however, is not satisfactory because contraction of the hot metal after the welding is apt to result in the breaking of the weld causing the identification plates to fall off. This difficulty is aggravated by scale formation occuring on the newly rolled metal articles, and which makes the welds insecure.

The difiiculties characteristic of prior art identification procedures for hot rolled articles are obviated by the apparatus of the above-mentioned copending U.S. Patent No. 3,368,730. Thus, the apparatus of this patent, which is designed for applying identification plates and the like to hot rolled articles, comprises a cartridge-actuated fastener driving tool, locator means for locating an identification plate relative to the tool for securing to an article by the tool, a support mounting the tool for displacement thereof between an operative position, in -which the tool and the locator means confront an article to be marked, and an inoperative position, in which the tool is displaced from the operative position. The tool further includes a cartridge chamber for receiving a cartridge and remote actuating means operable to actuate the tool, as by detonating the cartridge, when the tool is in its operative posltlon.

The remote actuating means may be electrically operated, pneumatically operated, or hydraulically operated and is effective to impact a firing pin of the tool to cause cartridge ignition to operate the tool, or may be an electrical arrangement to detonate an electrically detonatable cartridge.

There has recently been developed a new form of cartridge which differs radically from conventional or known cartridges in that it comprises a casing of a molded plastic material, such as nylon or polyvinyl chloride. A cartridge of this type may be constructed for impact detonation in the conventional way, or it may be provided with electrical contacts for the `application thereto of an electric potential to detonate the charge contained within the plastic casing.

These newer cartridges have certain definite advantages over conventional cartridges, particularly where cartridges are to be employed in hot locations. In the first place, when a plastic case cartridge is constructed for electrical detonation, it does not require the provision, on the tool with which it is to be used, of any moving parts such as a tiring pin, to achieve detonation. In the second place, a very simple and safe electrical circuitry can be employed to detonate a plastic case cartridge. In the third place, and this is very important, such a cartridge will not detonate unless a predetermined voltage or potential is applied thereto. Thus, at a potential of less than about 60 to 90 volts, no detonation whatsoever will occur. Between about volts and rated voltage, for example, 220 volts, only slow burning rather than rapid detonation occurs. It will be appreciated that this provides an important safety factor.

As an additional advantage, the cartridges will not detonate under the influence of heat. What happens, as a matter of fact, is that the cartridge casing tends to become plastic and to fuse, with the result that any ignition of the charge does not result in the production of rapidly expanding gases within a confined space. On the contrary, the charge merely burns slowly and has no explosive effect.

SUMMARY OF THE INVENTION The present invention is directed to an improved construction of the cartridge-actuated fastener driving tool particularly adapting the latter for use with an electrically f detonated plastic case cartridge. Thus, the remote actuating means of the apparatus is preferably in the form of an electric circuit including a pair of contacts in the tool adjacent the cartridge chamber for engaging cornplementary or mating contacts of a plastic case, electrically detonatable cartridge.

The electric detonating circuit includes means for applying, across the contacts, a suitable cartridge-detonating voltage for operating the tool. This latter means may comprise a capacitor adapted to be charged from a current source and, for cartridge detonation, to be connected to the contacts to discharge therethrough. The current source therefore may be provided as a storage battery. Alternatively, the current source may be the high voltage winding of a voltage step-up transformer, or it may be an appropriate electronic power pack selectively operable to provide a high voltage signal.

Accordingly, an object of the invention is to provide improved apparatus for securing identification plates, or the like, to articles, such as hot metal billets.

Another object of the invention is to provide an improved and simplified cartridge-actuated fastener driving tool.

A further object of the invention is to provide such an improved cartridge-actuated fastener driving tool particularly adapted for use with electrically detonated plastic coat cartridges.

Still another object of the invention is to provide such an improved cartridge-actuated fastener driving tool including an improved closure construction for the cartridge chamber. l

A further object of the invention is to provide an improved cartridge-actuated fastener driving tool including a novel and improved remote control electric circuit means for detonating a plastic coat cartridge.

BRIEF DESCRIPTION OF THE DRAWINGS For an understanding of the principles of the invention, reference is made to the following description of a typical embodiment thereof as illustrated in the accompanying drawings.

In the drawings:

FIG. 1 is a fragmentary side elevation view, partly in section, of a cartridge-actuated fastener driving tool embodying the invention, together with associated cornponents; and

FIG. 2 is a schematic wiring diagram of a preferred electric detonating circuit for the tool illustrated in FIG. 1.

DESCRIPTION OF THE PREFERRED EMBODIMENTS Referring to FIG. 1 of the drawings, the apparatus of the present invention includes a supporting structure which is identical with that disclosed in said U.S. Patent No. 3,368,730, and including an overhead carriage displaceable, on rails, toward and away from a workpiece. These already disclosed elements have been omitted from FIG. l in order to simplify the illustration. However, with reference to parts associated with the supporting structure, the same reference characters have been used in FIG. 1 of the present application as used in the mentioned copending application, such as webs 21 depending from the carriage.

Thus, and as illustrated in the mentioned patent, the lower ends of webs 21 have secured thereto a substantially horizontal base plate 22 forming part of a fastener driving tool assembly 23 including two or more fastenerdriving tools 24. Tools 24 are connected to webs 21 by pivots 27 inserted through apertured ears in base plate 22. Each tool 24 comprises a casing-25 enclosing a plunger (not shown) which is displaceable, by cartridge detonation, to drive a fastener (not shown) from that end of a telescopic barrel section 39 upon which there is mounted a base plate 47, when barrel section 39 has been abutted against a fastener-receiving surface .4 and displaced inwardly of casing 25 lsuiicient fora switch abutment 76 on base plate 47 to depress a switch operating plunger of a switch mounted on a front plate 7-4 between webs 21.

A catch 59, biased by a spring 60, engages with a hook 34 on casing 25 to hold a tool 24 in its illustrated operative position. Manual depression of catch 59 releases hook 34 to permit a tool 24 to swing down labout its pivot 27 for loading and unloading purposes.

All of the above is already described in U.S. Patent No. 3,368,730, and more particularly in the embodiment of FIGS. l through 6 of the drawings thereof, FIG. 7 of the drawings of the mentioned patent illustrating a different tool construction.

Referring again to FIG. l of the drawings of the present application, tool 24 is illustrated as loaded with a plastic case cartridge 201 in its carriage chamber. Cartridge 201 has two electrical contacts 202 and 203 exposed, in spaced relation to each other, at the base thereof. With tool 24 in the illustrated operative position, contact 203 engages a metal bush 204 set into plate 22 in registry with the cartridge chamber of tool 24 when the latter is in its operative position. Metal bush 204 has extending therethrough an axial contact pin 205 for engagement with Contact 202, contact pin 205 being located in position in bush 204 by tubular inserts 207 of dielectric material. Positioning of pin 205 is secured by a locking cap 208 screwed into the upper end of bush 204.

In accordance with a feature of the invention, pin 205 is formed with an annular flange 206 substantially midway of its length, and this enables the assembly, consisting of bush 204, pin 205 and inserts 207, better to withstand the explosion pressures arising upon detonation of cartridge 201, in a better `manner than would be the case if pin 205 were substantially of constant cross section. Bush 204 is screwed into plate 22 and must, of course, be disposed so that, in the operative position of tool 24, no gap occurs between part 209, defining the chamber for cartridge 201, and the confronting end face of bush 204. To this end, bush 204 is formed with a toothed circumferential flange 210 accommodated in `a recess in the bottom surface of plate 22. A screw 211 is screwed into plate 22 so that its head will engage in one of the gaps between the teeth of flange 210 yafter bush 204 has been screwed into the extent necessary for proper abutment with part 209. This anchors bush 204 against angular displacement, and two or more screws 211 may be provided to engage with respective tooth gaps of flange 210.

Plunger 75 serves, upon depression by plunger 76, to actuate a switch 212 secured to front plate 74. A lead 213 from switch 212 `makes electrical contact with contact pin 205 through a terminal stud 214 and an intermediate pin 215 carried by a bracket 216 secured to plate 22 by a bolt 217.

Referring to FIG. 2, the electrical detonating circuit includes a transformer 220 whose primary winding is connected to commercial supply means 221 through a main switch 222. The secondary winding of transformer 220 applies an appropriate voltage, such as a voltage of the order of from to 220 volts, to -a circuit including the two electrical contact tool parts 204 and 205 which engage the contacts 203 and 202, respectively, of cartridge 201. This circuit also includes a resistor 223, such as one of the order of 100 ohms, switch 212 and two further safety switches 224 and 225 as well as a carriageactuated switch 226. Safety switches 224 and 225 are arranged to be actuated, respectively, by hand and by foot pedal operation. Switch 226 is positioned so as to be closed only when the carriage is properly positioned ready for driving -a fastener into a receiving surface or workpiece, and to be opened when the carriage, and with it the tool 24, is shifted away from such position. It will be note'd that all of the mentioned switches must be closed before a potential can be provided between contacts 204 and 205 of the tool. The operation of the apparatus will be understood readily from the foregoing and from the description in the mentioned copending U.S. patent. In securing an identification plate to an article, such as a hot metal billet, casting, or the like, tools 24 are appropriately loaded with respective cartridges 201 and fasteners. An identification plate (not shown) is positioned on base plate 47, ready for driving the fasteners therethrough Iand into the article. Main switch 222 and manually operable switch 224 will have been closed.

The carriage is now shifted along its rails to bring base plate 47 into engagement with the article to be marked, and to cause barrel part 39 to be pressed into casing 25, as already described. Thereby, the carriage actuated switch 226 and switch 212 are both closed. Initiation of the fastener driving is then effected by the operator pressing pedal operated switch 225 thereby to complete the circuit for impressing a potential, from the secondary winding of transformer 220, across contacts 204 and 205 so that the secondary voltage is applied across the contacts 202 and 203 of cartridge 201 to detonate the cartridge.

While one particular electric detonating circuit has been shown in FIG. 2, it will be appreciated that other equivalent circuits can be used. Thus, for example, an equivalent circuit could include a battery, such as a dry battery or -a storage battery, in place of transformer 220, the battery being adapted to produce a voltage of about 120 to 150 volts. This lbattery would be connected in a circuit with the switches 224, 225, 212 and 226, with a resistor which can be of the order of 4,000 ohms, and a condenser. The appropriate voltage is then provided by discharge of the condenser. Other circuit arrangements which could be employed would include an electronic power pack arrangement of the type employed with photographic flash equipment and which produces a high voltage impulse as and when desired.

The advantages due to the use of electrically-detonatable plastic case cartridges in marking apparatus intended for use in steel Works and the like, under hot conditions, cannot be over emphasized, since these cartridges provide for immeasurably improved safety in comparison with known metal case cartridges. The latter must be struck or impacted to cause detonation, whereas the plastic case cartridges arranged for electric detonation cannot be set off by impact, so that no danger can arise from accidental knocking or striking of the plastic case cartridges. In steel and like industries, -where hot metal billets are being handled, there are severe and dangerous hazards in the use of metal case cartridges in that, if the latter should be subjected to elevated temperatures for too long of period, or if they should be dropped accidentally onto a hot surface, the charge of the cartridge may explode and cause rocket-like propulsion of the cartridge case which might result to injury to workers in the vicinity. In the case of a similar occurrence with a plastic case cartridge, the casing will simply fuse and burn quietly, as will `also the charge, so that the risk of injury to personnel through accidental heat detonation is obviated.

Additionally, the use of plastic case cartridges enables the structure of the fastener tool to be considerably simplified. The need for a mechanical or electro-mechanical tiring mechanism, as such, is eliminated, and such mechanism can be replaced by very simple electrical circuitry while, at the same time, providing for reliability of operation and adequate safeguards against unintentional operation. The elimination of the moving parts necessary both in the firing mechanism itself and in the means permitting actuation of the firing mechanism, where metal case cartridges are employed, represents a substantial factor in the reliability of the apparatus, since such moving parts are, of course, subject to wear and are an important inliuence on the overall working life of the apparatus.

What is claimed is:

1. In apparatus for securing identification plates, or

the like, to articles, such as hot metal billets, of the type including a cartridge-actuated fastener driving tool displaceable between an operative position, in which the tool confronts an article, and an inoperative position, in which the tool is displaced from the operative position, a cartridge chamber in the tool for receiving a cartridge, and remote actuating means operable to actuate the tool when the latter is in its operative position: the improvement comprising a plastic case cartridge in said cartridge chamber for detonation by application of an electric potential thereto; said remote actuating means comprising an electric detonating circuit lfor said cartridge; said cartridge having a pair of electrical contacts thereon; a pair of contact members in the tool engageable with the respective contacts of said cartridge; said electric detonating circuit being operable to apply a suitable cartridge detonating potential to said contact members; one of said contact members being a metal bush threaded into a stationary part of the tool and having an end face confronting said cartridge chamber; the other contact lmember comprising a pin extending axially of said metal bush and having an end confronting said cartridge chamber; said pin having a radially projecting flange, of substantial depth, intermediate its ends; a pair of dielectric members in said bush embracing said pin and engaging respective opposite surfaces of said flange; and means retaining said dielectric members against displacement outwardly of said metal bush.

2. In apparatus for securing identification plates, or the like, to articles, such as hot metal billets, of the type including a cartridge-actuated fastener driving tool displaceable between an operative position, in which the tool confronts an article, and an inoperative position, in which the tool is displaced from the operative position, a cartridge chamber in the tool for receiving a cartridge, and remote actuating means operable to actuate the tool when the latter is in its operative position: the improvement comprising a plastic case cartridge in said cartridge chamber for detonation by application of an electric potential thereto; said remote actuating means comprising an electric detonating circuit for said cartridge; said cartridge having a pair of electrical contacts thereon; a pair of contact members in the tool engageable with the respective contacts of said cartridge; said electric detonating circuit being operable to apply a suitable cartridge detonating potential to said contact members; one of said contact members being a metal bush threaded into a stationary part of the tool and having an end face confronting said cartridge chamber; said metal bush having a ange thereon formed with a circumferentially extending series of teeth; and a screw threadable into the stationary part of the tool and through a gap between a pair of Said teeth to prevent rotation of said metal bush after adjustment of the latter by threading into or out of said stationary part.

References Cited UNITED STATES PATENTS 2,576,473 11/1951 Meyers 227-11 X 2,931,039 4/1960 `Henning et al 227-11 3,171,063 2/1965 Hutchison et al. 102-28 X 3,181,730 5/ 1965 Schafroth 227-7 3,196,041 7/ 1965 McNulty 102-28 X 3,251,216 5/1966 Broske 227-10 X 3,261,528 7/ 1966 De Courteix 227-9 3,361,064 1/1968 Johnston et al 102-28 THERON E. CONDON, Primary Examiner N. ABRAMS, Assistant Examiner U.S. C1. X.R. 227-8 

